That’s not what the article says. It says the plotters planned to sue for peace, hence, why the first sentence says the war would end. I think you are getting confused, because they were initially going to blame the plot on a traitorous SS group. Read the article again.
How were they supposed to achieve this "peace" once Hitler was dead? Just ask Stalin nicely? The Eastern Front had already crumbled and the tide of war had turned. Furthermore, the US and UK were committed to Germany's unconditional surrender. The plotters may have hoped for a separate peace with the US and UK was Hitler was gone, but such a deal was unlikely, and they'd have to keep fighting the Soviets regardless. The writer of this article would probably blame the Allies' unreasonable unconditional surrender demand for prolonging the war unnecessarily.
I get really tired of hearing about how these German resistance plotters were a bunch of great heroes. Von Tresckow was connected to Stauffenberg and the circle around Admiral Canaris. They were all loyal, patriotic German soldiers who knew that Hitler was flushing Germany down the crapper. They weren't on our side. They were on Germany's side.